sys/crypto/rc4/rc4.c

   1 /*
   2  * rc4.c
   3  *
   4  * Copyright (c) 1996-2000 Whistle Communications, Inc.
   5  * All rights reserved.
   6  *
   7  * Subject to the following obligations and disclaimer of warranty, use and
   8  * redistribution of this software, in source or object code forms, with or
   9  * without modifications are expressly permitted by Whistle Communications;
  10  * provided, however, that:
  11  * 1. Any and all reproductions of the source or object code must include the
  12  *    copyright notice above and the following disclaimer of warranties; and
  13  * 2. No rights are granted, in any manner or form, to use Whistle
  14  *    Communications, Inc. trademarks, including the mark "WHISTLE
  15  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  16  *    such appears in the above copyright notice or in the software.
  17  *
  18  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  19  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  20  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  21  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  22  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  23  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
  24  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  25  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  26  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  27  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  28  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  29  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  30  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  31  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  32  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  33  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  34  * OF SUCH DAMAGE.
  35  */
  36
  37 #include <sys/param.h>
  38 #include <sys/kernel.h>
  39 #include <sys/module.h>
  40 #include <sys/types.h>
  41 #include <crypto/rc4/rc4.h>
  42
  43 static __inline void
  44 swap_bytes(u_char *a, u_char *b)
  45 {
  46         u_char temp;
  47
  48         temp = *a;
  49         *a = *b;
  50         *b = temp;
  51 }
  52
  53 /*
  54  * Initialize an RC4 state buffer using the supplied key,
  55  * which can have arbitrary length.
  56  */
  57 void
  58 rc4_init(struct rc4_state *const state, const u_char *key, int keylen)
  59 {
  60         u_char j;
  61         int i, k;
  62
  63         /* Initialize state with identity permutation */
  64         for (i = 0; i < 256; i++)
  65                 state->perm[i] = (u_char)i;
  66         state->index1 = 0;
  67         state->index2 = 0;
  68
  69         /* Randomize the permutation using key data */
  70         for (j = i = k = 0; i < 256; i++) {
  71                 j += state->perm[i] + key[k];
  72                 swap_bytes(&state->perm[i], &state->perm[j]);
  73                 if (++k >= keylen)
  74                         k = 0;
  75         }
  76 }
  77
  78 /*
  79  * Encrypt some data using the supplied RC4 state buffer.
  80  * The input and output buffers may be the same buffer.
  81  * Since RC4 is a stream cypher, this function is used
  82  * for both encryption and decryption.
  83  */
  84 void
  85 rc4_crypt(struct rc4_state *const state,
  86         const u_char *inbuf, u_char *outbuf, int buflen)
  87 {
  88         int i;
  89         u_char j;
  90
  91         for (i = 0; i < buflen; i++) {
  92
  93                 /* Update modification indicies */
  94                 state->index1++;
  95                 state->index2 += state->perm[state->index1];
  96
  97                 /* Modify permutation */
  98                 swap_bytes(&state->perm[state->index1],
  99                     &state->perm[state->index2]);
 100
 101                 /* Encrypt/decrypt next byte */
 102                 j = state->perm[state->index1] + state->perm[state->index2];
 103                 outbuf[i] = inbuf[i] ^ state->perm[j];
 104         }
 105 }
 106
 107 static int
 108 rc4_modevent(module_t mod, int type, void *unused)
 109 {
 110         switch (type) {
 111         case MOD_LOAD:
 112                 return 0;
 113         case MOD_UNLOAD:
 114                 return 0;
 115         }
 116         return EINVAL;
 117 }
 118
 119 static moduledata_t rc4_mod = {
 120         "rc4",
 121         rc4_modevent,
 122         0
 123 };
 124 DECLARE_MODULE(rc4, rc4_mod, SI_SUB_DRIVERS, SI_ORDER_FIRST);
 125 MODULE_VERSION(rc4, 1);